You may be surprised to hear that there are between 138 and 300 sign languages used in the world. Their development is complex and many have family-like lineages. The main sign language lineages can be divided into four family trees: BANZSL (British, Australian and New Zealand Sign Language from the old British Sign Language), Danish, French, and Swedish.
Funnily enough, American Sign Language (ASL) comes from French Sign Language (FSL) and it is not related to British Sign Language (BSL). One of the most widely used sign languages in the world is Chinese Sign Language (CSL or ZGS), with up to 20 million users. Brazilian Sign Language has about three million users, while Indo-Pakistani Sign Language has around 1.8 million users across South Asia. Signers using different languages cannot understand one another as they are not mutually intelligible.
The following image shows the sign language family tree as of 2021:
Some (hearing) people are often surprised by this and wonder why there isn’t just one universal sign language so that every deaf person in the world can communicate with each other. Well, the simple answer is that, just like spoken languages, they developed independently over time in every part of the world. And just like spoken languages, some were influenced by larger and more dominant sign languages.
It is not just the signs that differ. The speaker’s facial expressions, gestures, and body language can all have a significant bearing on how a sign language is communicated. This is another reason why there are multiple sign languages: every sign language is different; every sign language user comes from a different culture and their approach to life and language is unique.
The case of the Nicaraguan Sign Language (NSL) is particularly interesting. It is considered by linguists as an example of a complex sign language being formed at lightning speed when children from around the country came together at a deaf school. Teachers tried to teach them Spanish Sign Language (LSE), but the students preferred to find their own ways to express themselves and they developed their own signs with increasingly complex grammar.
The World Health Organization estimates that around 5 percent of the world’s population is deaf. Professional sign language interpreters have the knowledge and the skills to understand and translate the subtle differences in sign language to a local audience. Although their presence in the public sphere has increased, there is still a lack of sign language interpreters so that deaf people can be fully integrated in society, especially in rural areas.
Interestingly, there is also an international sign language, with about 1,500 signs, used since the 1970s. It is called Gestuno or International Sign Pidgin. Like all Pidgins, it is drawn from several different signed languages (mostly European and ASL we would say) and it has a very simplified structure and minimal rules.
Sources:
-SignSolutions: https://www.signsolutions.uk.com/what-are-the-different-types-of-sign-language/#:~:text=There%20are%20more%20than%20300,use%20and%20understanding%20of%20signs.
-Hearing Like Me: https://www.hearinglikeme.com/sign-languages-around-the-world/
-“Deaf Education Without Borders” Facebook page